Below is an in-depth interview with Dave Horchler (pronounced Hork-ler), former GM Proving Ground engineer and Trans-Am racer. His car was the 16th Z-28 built and was sold through Van Camp Chevrolet in Milford, MI.

Trans-Am Racing RecollectionsA Conversation with Dave Horchler

By: Jon Mello

One of the very earliest Camaro Z-28s built, car #16 out of the initial batch of 25, was ordered by David D. Horchler, a young engineer at the GM Proving Ground in Milford, Michigan. This Marina Blue Z-28 with RS equipment was purchased with the intent of being a road racer in the SCCA’s fledgling Trans-Am series. It would compete head-to-head against the factory-backed cars, not to mention the numerous privateer efforts that also ran the series. While Dave and his racing partner Dick Hoffman worked for GM, they did not receive money from Chevrolet to campaign their racecar. These were the days when Chevrolet did little to help its racers other than offering technical assistance and making sure to catalog and homologate the necessary parts to field a competitive car. Chevrolet was fairly serious about adhering to the AMA racing ban of 1957 whereas Ford opened the purse strings on its racing budget to almost obscene levels and paid little to no attention to the ban. The following is an interview with Mr. Horchler and focuses on the late ‘60s, which most feel to be the heyday of the Trans-Am series.

(JM) Dave, can you please tell me how you got started in racing and what led you to racing the Camaro in 1967?

(DH) I have always had a strong interest in things automotive. That led me from a degree in electronics at the University of Pittsburgh to my first job as an engineer at the General Motors Proving Ground in Milford, MI. My home was a short drive from a road-racing course that belonged to the Waterford Hills Sportsman Club. I spent many weekends watching Tony DeLorenzo, Bob Clift, Jerry Thompson, Erhard Dahm and many others tear around that challenging 1.5 mile track, As luck would have it, I got infected with the disease. I was working hard, raising a family and teaching electronics at night to pick up some extra money when I went crazy and decided to give racing a try. My first effort was in the Camaro. Dick Hoffman and I both worked at the Proving Ground in Milford and became friends. Dick had done some racing in the Land o' Lakes region since he came from Minnesota. We decided to form a partnership which we called H&H Racing Enterprises. Needless to say, our wives weren't overjoyed. We discussed the Trans-Am series versus the SCCA National and Regional program and from our perspective it appeared that it was just as costly to run a campaign in the Nationals as it was to do the T-A series at that time. We saw a new product announcement of the Z-28 and of course heard about the program from other GM friends that were interested in racing. I ordered a vehicle as soon as the order forms would recognize the option. I believe this was around the middle of December ’66. The car was delivered in mid-to-late January and we proceeded to break in the motor running the back roads behind the Proving Ground until we had about 150 miles on it. Then we started to do the prep work that was allowable in the SCCA rulebook. We did most of the work at Dick's home in Milford and some of it was done at the Proving Ground because in those days employes were permitted to use the garages to work on their personal vehicles. This allowed us access to some machine tools that we didn't own.

(JM) When you chose the Z28 to race, was there a certain element of GM loyalty in your decision or did you firmly believe it was the best choice for Trans-Am and A-Sedan competition?

(DH) GM loyalty was a big factor, plus the fact that we could purchase the vehicle at huge cost savings through employee discounts. Those discounts were available on all of the production parts we could use or wanted to use. The accessibility to the parts was also a factor. Actually, there was never a time when we considered any other vehicle. When we decided to go racing, it seemed that it made no sense to go race for trophies. If there was any possibility of getting some small part of our expenses back, that made it clear that the series to race in at the time was the T-A and being connected to GM made the Camaro the only choice. Another factor in choosing the Trans-Am was the fact that the races allowed co-drivers (in some cases it required them) because both of us wanted the opportunity to drive. The rules at the time made a co-driver mandatory. The sprint races in the current T-A are quite a different situation. We would have needed two cars.

(JM) How long did it take you to get the car prepared?

(DH) The car was prepped in time for me to start driver's school at Waterford Hills in April. From there I went to Grattan for the second school and then started to run regionals to get my National license. I got the National and FIA license in August, in time to run in the endurance race that was held in Marlboro that year. That was in early August of ’67. The following year we ran a number of races, some successfully and some not. We continued to develop the car and incorporate changes throughout the first year. The second year we basically changed only the engine to pull slightly more horsepower and replaced worn parts or those that could be strengthened through heat-treat or shot peening. You didn’t ask, but I believe we had a pretty decent Trans-Am record in the series. In 1967 after a DNS at Lime Rock, we finished 6th in class at Mid-Ohio and then 7th overall at Marlboro. In 1968 we ran Sebring, finishing 28th overall and 10th in class. Following that we ran Mid-Ohio, finishing 7th in class, 10th overall; Meadowdale finishing 6th in class, 9th overall and followed that up with DNF’s at St. Jovite and Watkins Glen. I should also mention that in all of the SCCA regional and national races I ran with the car my finishing position was never lower than 4th and that was in my first national race at Nelson Ledges.

(JM) What was your job at GM back in those days? Did you do any development work on the Camaro in general or the Z-28 in particular?

(DH) I did not have any specific job assignment relating to development of the Z-28. My job was in the Engineering Staff (corporate) during that time. I worked on a lot of programs such as brakes, transmissions, and engine development but generally not for a specific vehicle. Many of my assignments were in the area of developing specialized instrumentation that could be used to collect and analyze vehicle development data.

(JM) What was the first Trans-Am race for the H&H Camaro?

(DH) The 1967 Lime Rock race was the first Trans-Am we attempted. Dick Hoffman and Gib Hufstader were going to drive the car since I was still in the process of getting licensed. Unfortunately too many Porsches showed up for that race and we were not quick enough to qualify. That was the last time that happened! If you look at the results for that race, we were not listed. The first Trans-Am race our car actually ran in was the Mid-Ohio race in June of 1967 where we finished in the top ten. My first Trans-Am race was at the Marlboro, MD track in September of that year. As I mentioned earlier, we finished that race in 7th place.

Picture taken at Waterford Hills, 1967. David Horchler collection

(JM) Is there a particular reason for you choosing the #48 for the car? It appears to have always run using that car number.

(DH) It was simply based on our initials. We chose 48 as our number since “D” is the fourth letter of the alphabet and “H” is the eighth letter. We only changed the number one time that I remember and that was for the ‘68 Sebring race. Our co-driver Joie Chitwood wanted to use 17 on the car.

(JM) In 1967 you had white trim on the lower four corners of the car. Was there a particular reason for that?

(DH) The white trim on the lower sections of the car was white contact paper. Our low-buck way of doing decals at the time. One roll from Kroger or ACE Hardware lasted a long time. It was helpful in making the car easy to spot on the track and also protected the paint. There were lots of rocks and gravel flying on some courses.

(JM) What did you do to your engine to prepare it for racing?

(DH) In 1967, our only engine prep was at the first of the season when we blueprinted the engine. Otherwise it ran untouched through every race we entered that year. We should have stuck with it because we blew two engines in 1968 while running in 5-6th places in races at St. Jovite and Watkins Glen. The engines in 1968 were tweaked slightly for more power, but we wanted to endure the races as opposed to trying to beat the six-eight factory cars from GM, Ford, and AMC. Our objective was to be the best finishing private entry in the over 2-liter class.

(JM) I believe there was a problem with defective axles that first season. Do you recall anything about that?

(DH) GM had determined that a group of axles had received a bad heat treat at a critical area near the hub. The week of the Marlboro race (August ’67), they loaded up a station wagon and sent two guys off to the track to replace as many axles as they could. Our axles were original and we were not concerned, however we did change them out. I know that not all of the Chevy guys were recipients of the "good" parts. I suspect that the #4 Johnny Moore car did not receive the new parts as he broke an axle midway through the race. The two guys that came to the track were Paul Pryor and Bill Howell. Bill Howell was the engine guy who worked a lot on the dual quad set-up in 1968. Paul was more of a chassis guy. They worked for Vince Piggins who ran the Chevy race activity at the time.

(JM) I know you ran the Sebring 12-hour race in 1968. Why didn’t you try your hand at the Daytona 24-hour?

(DH) In a word, money. We were short for the season and without any sponsorship to speak of. We did not do a good job of looking for sponsors or selling a ride for the race. We decided to conserve our funds for the races that were close to our home base. Chitwood came along and rented a ride, which helped us go to Sebring. In spite of our penny-pinching, we were essentially out of funds by the time we got through with the Watkins Glen race that year. We missed most of the races after that.

Sebring 12-Hour race, March 1968 photo by Bernard Cahier

(JM) I thought it was interesting that Joie Chitwood drove with you and Dick at Sebring. Can you tell me more about how that came about?

(DH) We were looking for sponsorship for the race and his name came up via Vince Piggins. A few phone calls were exchanged and we subsequently agreed to the ride with him, essentially renting a seat. We had the car pretty well prepared for the race except for the late addition of the dual carburetor setup that was homologated in late 1967 for the car. Bill Howell, a GM engineer, came down to the race and assisted with the setup. He tried different jetting and modified the accelerator pumps to get the system balanced to get it to deliver the power seen in dyno testing at the lab in Michigan. We started the race pretty well with Joie driving and dicing with the big guys in our class. He was complaining about the performance of the engine system --- in essence, the carburetion. At driver change I began driving and had a flat tire at the hairpin after locking up the brakes there. Very embarrassing. Dick Hoffman carried a tire and wheel out and we changed it on the course and got back in. The car continued to suffer from the carburetion malady and finally Bill Howell asked us to come in for a round of adjustment and re-jetting. This took about an hour and a half. Chitwood became disenchanted and didn't hang around too long during this time. We finally got back in and finished the race with Hoffman and I doing most of the driving. Chitwood drove for a short time. We finished 28th or so overall and 10th or 11th in class. I have the official results somewhere in the archives. I guess that it was not a special time for Joie and we had no further activity with him throughout the year. I guess he expected much more than he received. In 20-20 hindsight we should have stayed with the single four-barrel Holley that served us well throughout the previous year. Lesson: never go racing with untried parts or technology, unless you are Jack Roush, Penske or the like, with resources to run two or more cars.

Sebring 12-Hour race, March 1968 photo by Pete Biro

(JM) Was there anybody else who co-drove with you two at another Trans-Am race?

(DH) Gib Hufstader was the only other person. As I mentioned previously, he and Dick tried to qualify the car for the ’67 Lime Rock Trans-Am (which didn’t pan out) and then he co-drove again at Marlboro with Dick and I. Gib has a long history as a Chevrolet engineer with the Corvette group. He could really give you a history lesson. He was a steady driver who saved the car while going fast as well. He and I remain friends today.

(JM) I saw that you ran at Meadowdale in ’68. That track has always intrigued me as my family moved nearby just a few months after the one and only Trans-Am race which was run there. What do you recall about that particular track?

(DH) That course was scary. It had no run-off areas and was narrow. As you came to the start-finish line in an uphill turn, the camber change at the top of the hill had cars jumping sideways and there were some collisions at the top of the hill. After the start/ finish line the track went downhill into a banked carousel turn, as I remember. This led to a long straight in a valley of sorts that was tree-lined and sort of like running into a tunnel of trees. Then there was a real tunnel under the entrance road, as I remember it. I have the program from that race and I think it has an outline of the course. Dick Hoffman drove the entire race that day. I had the flu and was woozy all weekend so Dick did the whole thing. I think he finished sixth or something like that. I think that was a Donohue, Titus, Follmer battle for the win, but will have to check the results sheet to be sure what happened.

(JM) So, you did not actually get to drive the course because you were sick that weekend?

(DH) I did manage to get in some practice laps but that was all I could handle. I just didn’t feel well enough to run the actual race. I might note that the SCCA records don't always reflect the co-driving we did correctly. There were some times when Hoffman's name appeared in the results and he did not participate --- business or personal schedule conflicts. The same held true for me. Sometimes we both didn't really get in the car at particular events. For example, in 1968 I drove the entire Mid-Ohio race and Dick was sick. At Meadowdale, we reversed that situation. He drove the entire race and I sat out with the flu. We weren't sticklers for detail then. I have a record of all of the ups and downs in my archives.

(JM) Are there any other race tracks that stand out in your mind that you could talk about --- maybe one that was particularly challenging, dangerous or one that you considered your favorite?

(DH) I like the Mid-Ohio track for its challenging turns and elevation changes. It was always well maintained with good runoff areas in critical spots even in 1967. It has continued to improve. Also, as small as it is, the Waterford Hills Sportsman’s Club track in Waterford, MI is a great place to hone skills on a tight course. It goes without saying that Sebring and Daytona are great race venues. The high speeds and, in some cases, high rates of closing on other cars make them challenging. I was not unhappy to see the closing of Meadowdale since its expansion potential was severely limited and it was dangerous in spots. I think the most ridiculous track was at Wilmot Hills in Illinois where we ran a regional race. Two turns separated by two dragstrips. Eddie Wachs was a terror in his Alfa on that track. Can’t leave out Road America and Watkins Glen as great racetracks, though my races there were in later years in other cars.

(JM) It is common knowledge nowadays that the Penske team received many one-of-a-kind experimental parts when they were running their Camaro racing operation. Things such as unique steering components and internal engine pieces, for example. Because of your connection to GM and friendship with people such as Bill Howell and Gib Hufstader, who worked very closely with the Penske team, did some special and unique parts end up getting tried on your car as well?

(DH) We were able to acquire some parts more quickly than other people were as they were released to service parts organization. Dual carburetors and the two-piece manifold would be a case in point. We also tried various steering and axle ratio combinations that were already part of the GM parts list but not released for the Camaro. During 1968 there were many opportunities to talk about the development of the car with Mark Donohue during and after their test sessions at the Proving Ground. He often shared not only the information about changes to the car, but his ideas on other areas that had potential for improvement. Two or three times a week I visited the Chevrolet garage at the Proving Ground where he had set up shop. Roy Gane, a Penske technician and Bill Horton, a Chevrolet technician, along with a Chevrolet brake engineer, Dick Ryder were frequently there with Mark. Lots of worthwhile discussions took place during those visits. In some cases we were able to fabricate bits and pieces for trial and error testing on the car. I don’t believe that Mark ever directly gave us any parts, although Bill Horton kept us up-to-date, so to speak.

(JM) What tricks, cheats, or “loose rule interpretation” specifics did you try that made it into the car?

(DH) We did some things to the car in the area of chassis changes. We were never fully able to evaluate their effects by testing. Almost everyone staggered the rear shock absorbers to somewhat deal with axle tramp and windup. We tried lowering the attachment points for the upper control arms to get an altered camber change curve for the car. All of the bushings were replaced with either solid or very high durometer material. The solid bushings were machined of aluminum. At one point I believe we tried some revised mounting of calipers, which we abandoned before ever running a Trans-Am with that setup. Another change was in steering gear ratios to provide faster steering response. As a side note, the lowered attachment points for the control arms was detected at the Mid-Ohio T-A by John Timanus, scrutineer, and both Donohue and I started next to the rear of the field. Mark gained about 15 places on the start and I got seven or eight by following him up the middle of the field. We think Timanus had a tip from someone because he went straight to the control arms in the tech inspection.

(JM) With your engineering background, what did you think were particular strengths and weaknesses of the Camaro, and just as interesting, what did you think were strengths and weaknesses of the competition?

(DH) Our situation was such that we never bothered about the competition. We concentrated what time we had on making our car faster. I have a strong feeling that for non-factory efforts, of which there were many, the only thing separating the cars was the drivers. I was not aware of any significant competitive advantages relating to the vehicle each started with. Everyone was on a learning curve with the cars and the regulations. When preparation of the cars began to play a big part, it was in the stiffening of the chassis (mostly through engineered roll cages), getting the weight down (acid-dipping or bodies-in-white) enough to be able to add weight for balance, use of materials that looked like production parts enough to fool inspectors. I think all of the cars that were in Trans-Am over two liters were on a pretty level playing field if they started life as a production car. The teams that had true factory support and were professional racers made each new year in Trans-Am more of a factory competition. I say this because they were the only people who had resources to devote to the effort full-time --- time, money and people. I always thought that the Camaro and Firebird wound up with superior braking capability and the engines had the edge over the Ford, Chrysler and AMC products. The Mustangs prepared for Parnelli Jones and Jerry Titus had some advantage in handling that seemed more evident on the tight courses (Lime Rock). Again, there is a lot to do with the drivers. You can point to the time when Penske and Donohue went to the Javelins. It didn’t take them long to get competitive! I think there is a parallel or analogy to the NASCAR situation today. Lots of very competitive cars with a formula for building them, which is where the T-A series was heading in the early days.

(JM) How long did you continue to run the car?

(DH) The 1968 season was the last for the car while we owned it. We then put it on the market and it was subsequently sold. The new owner, Levester Lewis, ran it in some Trans-Am races up to 1972. As I remember the car was not well prepared and he did not have a good, knowledgeable crew. He persisted and wound up finishing some races in SCCA (A-Sedan), but his Trans-Am results were not very good. I have attempted to contact him to find out where our car went after he completed his racing, but to no avail.

(JM) I have seen in SCCA records that Dick Hoffman ran a 1970-model Camaro in the Trans-Am series. Were you involved in that effort also?

(DH) Dick continued on to build another one or two cars with the 70-½ body style, which he campaigned in the early 70’s. I believe a man in Grand Rapids, MI owns one of those cars and the other may be in Canada. I helped Dick some in the early going on those cars, but my family was growing, my job was intensifying and my wife was unhappy. I stopped any racing activity about then—my first retirement from racing.

(JM) I am aware that your old racing partner, Dick Hoffman, passed away in an automobile accident several years ago. What can you tell me about Dick as a friend, work-mate and racer?

(DH) First of all Dick was a good friend. We related well and got along well through all of our partnership years and right up until the time of his untimely death. Dick had a rare combination of talents. He was tireless and relentless in pursuing the build of our racecars. He spent lots of hours in prepping the car alone when my work schedule interfered. He had a lot of curiosity about how things worked and what to do about making them work differently. We always got along fine with hardly a ripple in the stream. He was one of those people who you could converse with after not having seen or talked to him for months and the conversation would flow as if it was only yesterday that you talked. Dick was a cool and careful racer with good judgment about when to be aggressive and when to go with the flow of things. He had a great deal more seat time than I due to his amateur racing in Minnesota prior to joining GM. It took me the full first year to get to the point where we lapped courses equally as well.

(JM) Lastly, are there any other interesting Proving Ground stories you can share such as when Donohue secretly brought his car there for testing?

(DH) This is one area where my recall really fails me in the details. I spent a lot of time in the little shop where Mark and his helpers, Roy and Bill, did their work. I saw lots of plots of data from the Chevy R&D telemetry and listened to the discussions of the evaluation of this and that change that was being considered. None of these stand out in my mind as unique or unusual because they were typical of car development processes in use throughout the Proving Ground. Dick Ryder, the brake engineer, was frequently there when the brakes were being evaluated. Bill Howell, the Chevrolet race group powertrain guy, was also around from time to time.

As I mentioned earlier, at that time in the Proving Ground history employees were permitted to bring their vehicles into the garage areas and work on them after hours. Dick and I did a lot of the work on our car in the garage of the department in which I worked. There was a hoist and a machine shop that we could put to good use. Our roll bar/cage, such as it was, was installed there in the PG and we did a lot of the weight reduction work on the car there. It was difficult in that we had to itemize any production parts we took into the facility and show the list to Security when we entered the property. Security frequently came around to check on whether we were abusing the privilege. At that time in our careers, we were so concerned with retaining our jobs any thoughts of misappropriation of GM property were quickly dismissed. We kept very accurate records (receipts) of every part we ever acquired for the car. I think I may still have some of those hanging around somewhere. I don’t like to look at the prices then versus now. The days of employees working on their personal vehicles on or in General Motors facilities are long gone. We were never able to have our car on the Proving Ground road system for any type of testing. Maybe if we had been winners like Mark, the door would have opened.

On a side note, at the Proving Ground I did have the experience of seeing the Corvette Grand Sport cars returning to the Chevrolet garage from the Nassau races. That was in 1963 or 64. Many years later I met and have become friends with Bill Tower who owns the Grand Sport Corvette that Penske drove that year. Bill has done a complete restoration on the car and it is a lot cleaner than it was when I saw it at the Proving Ground. Bill happens to possess the Corvette that I had been running in the 1980-1984 time period in Waterford Hills and IMSA races. He tracked me down to get information about the car, which is in dire need of restoration. That, however, is a story for another time.